I'm at a loss now. We're a group of friends who are all pretty new to DnD. We're interested in unlocking some of the classes, spells and items, but it's hard to figure out what is locked behind paid content and what's simply not present on DnDBeyond.

One example of this is Repelling Blast. There are descriptions of it, but the spell itself can't be selected as a Warlock? Is it locked behind paid content? Is it simply not available on the site? Can someone please dumb it down for me, cause I was halfway towards purchasing a yearly subscription when I realized that doesn't unlock any spells, races or classes either.

It's difficult to figure out where to start. 

Free Stuff: https://www.dndbeyond.com/sources/basic-rules

There's also Unearthed Arcana (playtest) stuff and Frozen Sick adventure.

Everything else requires purchase.

Repelling Blast isn't a spell. It's an Invocation you can select using the Invocations class feature from 2nd level onwards. It amplifies the use of Eldritch Blast if you have it.

Eldritch Blast (cantrip spell) and Repelling Blast (Invocation) are part of the free rules. Make a Warlock, give them Eldritch Blast cantrip, level them to 2nd level, and in Invocation class feature select Repelling Blast from the drown down menu.

If you want to make purchases you can click Marketplace at the top, then Store. From there you can view the sourcebooks and adventures. From sourcebooks (which often give player options like races, subclasses, spells, etc) you can choose to buy the individual option instead of the whole book, if preferred. The sourcebook price will be discounted by the amount paid should you want to get it in future, but until then buying individual options might be better if you're on a budget.

Subscriptions are only to remove ads, get unlimited character slots, get early access to upcoming tools, and for the master tier, share any purchased content with your group.

If you are just starting out and don't want to spend too much money, I would either buy the PHB, or just the content you need (races / subclasses).
Other good books with high content to cost (for character creation) are

• Xanathar's Guide to Everything (subclasses and spells)
• Explorer's Guide to Wildemount (races)

If I purchase individual items or other "Additional Purchase Options" ala cart from a source book, do I get access to the text in that section of the digital book, on dndbeyond?  I'm interested in both getting playable races/subraces/classes/subclasses/spells/feats (perhaps magical items), etc for character sheet, but also would like to have access to that information in text. 

Also is there some kind of a resource that somebody has already created for figuring out how to make purchases either efficiently, based on the classes, etc that  you like to play?  Or on how to get AlL the character sheet content, if that's your thing?  

I'm  asking as  player, not DM: I'm not especially interested in purchasing information related to running campaigns or monsters, etc, unless there is a good reason to make a purchase that includes that information.

You don't get access to reading it in book form, but you'd be able to access it in the various rules pages, and in the character sheet. For example, if you bought just the spells from EGtW, you wouldn't be able to go to the source page for that book and read the chapter on spells, but if you went to the spells page on DDB, and filtered to EGtW in the advanced filters, you'd be able to read the full entries for all the spells there. Same with going to the races page or the the page for any given class.

Quote from pocketmouse >>, but if you went to the on DDB, and filtered to EGtW in the advanced filters, you'd be able to read the full entries for all the spells there. Same with going to the or the the page for any given class.

"but if you went to the spells page on DDB, and filtered to EGtW in the advanced filters, you'd be able to read the full entries for all the spells there. Same with going to the races page or tthe page for any given class."

***** EDITED TO SAY "Game Rules** instead of  "General Rules"*****

Thank you so much for the reply!  Just to clarify, You're talking about under the Game Rules Tab, Right?  

 I  played around with it a little and now I  think under Game Rules, dndbeyond gives us access to some information on, I believe,  all the Classes.

 It looks like information on some/many Subclasses, Races, Feats, Backgrounds, Magical Items, Monsters, and Vehicles are conditional upon purchasing .  

I can't tell for sure (and constantly) about Spells  (or regular, non-magical Equipment).  

I'm talking about the 'Game Rules' tab in the megamenu up top -- everything there is a link, including the words 'classes' and 'spells.' If you buy things a la carte, you can definitely see it on those pages. DND Beyond generally, across the site, provides free access to what WotC has provided for free, usually labeled as 'Basic Rules,' which includes about a third of what's in the PHB (eg one subclass per class, except for the artificer, which wasn't in the PHB).