I've been messing around with homebrew content lately and when i add a spell to a magic item ( the magic item casts spells) it doest show up on the page

You have to set a “Minimum” and “Maximum” number of charges and add charges to the magic item. 

i did, does it have to  be different for each min and max (for example if i set min to 2 cam max also be 2)

Yeah, that’s no problem.

Please see the General FAQ #s 6 & 6-B and the Items & Equipment FAQ #6: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/131411-a-homebrewers-how-to-faq).

so do magic items only show what spells they can cast when they are equipped? because I don't see it in the preview

Edit: the item is armour

The “preview” would only display whatever you entered into the description field. The spells will only show on the character sheet when equipped (and attuned if necessary).

thanks that helps a lot you solved my problem :)