Just ride the bike if/when the brakes won't stay adjusted get some now ones and better pads same with grips, and tires but be careful with the tires they can be expensive.
If it turns out you like riding bikes my focus would be on getting tools not parts for your bike, bottom bracket tools, cassette/freewheel tool, cone wrenches, chain tool, cable cutter. In a couple years you will have enough tools and probably money to find a better canvas and perhaps the skills and knowledge to build from a frame.