Intro 2? Kinda

[Noh0nda]

Ok so I've been on this forum and posting for awhile but i though I might as well blow some time with this. My name is Brandon i am 17 and i live in Las Vegas nv and i recently bought a 1990 240sx all stock I've wanted one for a long time just finally had the money and found one for 1400 because it was over heating. I'm an aspiring mechanic so i saw that has an amazing deal specially since I did a block check oil etc there to make sure head gasket wasn't blown. I haven't really ever driven older cars so just about every grind/rattle worries me. My transmission grinds when i go into first at a stop for no reason,moves sideways about 3-4 inches in a gear and wont go smoothly from 1st to 2nd without it kind of moving sideways a little all building up to making me think it needs to be rebuilt. Trying not to Assume to look like an a** just hoping to learn as much as I can about my car as I can from this forum. Thank you