Any guides on how to play using the digital character screen?

Ive been using a paper character sheet and thought I would try the digital one with our new campaign. The creation of the character was really nice and straightforward. However using it during gameplay isn't as intuitive, 

Are there any guides on gameplay? for example, adding gold found or recording experience points, or a magic item reward - adding it both as an object (such as a sword) as well as stat modifier (+1 sword) or do I keep track of the modifiers in my head?

Another example: I have proficiency with the dagger. on the sheet it shows "nick" in the notes field for my mastery but I can't find anywhere it tells me what that is. Do I need to leave the sheet and dig up the rule book to look it up or am I missing how to do it.

I'm not sure if there are any existing guides, but I can offer some quick answers to some of your questions.

Gold: Go to your inventory tab, click on the gold. The sidebar pops up with a section labeled "Adjust coin". Input however much you want to spend or gain and click the appropriate button.

Xp: Click on the xp bar under your character's name. On the sidebar popup, click "Manage Experience". The new sidebar menu allows you to add or remove xp, or set xp to a specific amount. Note that when you level up, you will need to go back to the builder to make any choices for your new level.

Magic items: magic items can be added to the sheet. On the inventory tab click "Manage Inventory". Under "Add Items" you can search for and add any items, such as a Longsword, +1. The bonus for the longsword is tracked automatically.

Weapon mastery: you can only use the mastery properties of the weapons you have mastery in. These are displayed with a little star above the weapon symbol on the left when you're looking at the actions tab. If you click on the weapon name, the sidebar will pop up to explain its properties. The mastery properties (such as Nick) will only be displayed for weapons with which you have mastery. If you don't have mastery with the weapon, its mastery properties are hidden in the sidebar.