u/InNeedOfAnwers

I recently got into cycling, and I bought a preassembled Walmart Ozark Trail G. 1 Explorer as a starter bike. I heard it's best to get a basic tune up at a local bike shop. I've noticed some obvious issues with my bike already. There's chain rub on the front derailleur, and my chain falls down to the smaller sprocket by itself when I shift to the largest sprocket. Are these issues that can be fixed with a tune up? I've been eager to continue riding, but I want to ensure my bike works properly. Where can I get a basic bike tune up for a reasonable price?