Advice needed regarding gear indexing

Do you have an inline or inframe barrel adjuster? If so unpinch the cable, tighten the barrell all the way in then a half turn out. Make sure you click the shifter many time so that it would be at the small ring. Pull the cable hand tight and clamp it. Try shifting. If it doesn't go up adjust barrel adjuster until it does. Not likely but could also be limit screws. Sorry that all I know.

Parktools do a good selection of howtos. Here's one on front derailleur adjustment: https://www.parktool.com/blog/repair-help/front-derailleur-adjustment

It sounds to me like you don't have sufficient tension in the cable, but I'm no expert.

Is it a band type?  Making sure you have the correct height and that it is parrallel to the big ring are important.

When new a front deralier should have a little bit of plastic to expand the parallelogram, an hex key will suffice, and the sticker on a shimano lets you line up the height witht the big ring.

Please ignore if it is attached to a braze on.

This is a simple enough job, when you've done it a few times.  It involves a dozen or more discrete steps and each one would take half a page of description, so I suggest for your first attempt you look at a YouTube video or two, Art's Cyclery do a good one.

Congratulations on the paint job, it's something I've never tackled but one day .....