can anyone help me with bicycle maintenance? my trek bike is 3 years old now and the only thing i have done is washed the bike, chain, gears, and oil them. i also do the brakes decently but they are usually pretty loose.

anyways i need help adjusting the gears and truing the rim.

i looked on websites where it had an easy guide for any fool to do, but it was way too hard with weird tools i dont have for truing.
i would like to do it myself and not pay 100 dollars for a full tuneup, im a poor college guy

ok sorry for the bad grammar and shit thanks

pic of some bike