If you go to the How To forum, you’ll see a few “stickies” at the top of the list of topics, including one entitled something like “the solution to when your stockinette stitch is curling”. You might find that interesting to read through. Even though you did a garter stitch- which I’ve never had curl, although Sue says that it can happen if the scarf is very narrow.
But as to your blocking question-- first of all, no question is too silly around here:) . We all went through the process of learning all the bits and pieces! Blocking is when you apply moisture, and often heat, to something you’ve knitt to set the stitches. It’s often permanent, but not always. It will make everything look very nice and neat and professional, and it can also stretch out a piece. It’s amazing what it does for lace knitting. Most acrylics can’t be blocked, most wools and other animal fibers can. When Sue said don’t apply pressure, that’s because you don’t want to flatten your work. There may be a video here on the site about it, or pictures on line, in you Google the words blocking and knitting, or something along those lines.
If your scarf is made from a yarn which is wool, or mostly wool, you can do it-- just wet it thoroughly, roll it up in a Turkish towel and squeeze out as much water as you can, and then lay it out to dry. If you can pin down the edges on something such as an ironing board, that’s best. (Rust proof pins!) You can hold a hot iron an inch or so above it and just slowly go over the whole thing and then let it dry thoroughly, pinned down. Wool holds a lot of moisture, so let it sit for a few days. If it’s a very long scarf, you may need to do it in sections.
Welcome to the world of knitting, and to knittinghelp!