How do I make regular computer paper look like it's 100 years old?

Wet a tea bag and (after squeezing slightly) lightly press it onto the paper, this will make the paper go brownish and slightly crumpled. Burning the edges would be good but this is quite risky (especially if your work is already printed) so you might want to carefully tear a few edges. Hope that helped :)

make it into a ball, then smooth it out again. Do that a few times, then really carefully rip the edges so it's not perfectly clean-cut, then move it carefully over the tip of a flame to brown it. Just be careful not to set it on fire

throw some hot coffee on it

Type your assignment then use COLD water to wet a teabag and smear it over the paper. Then use some instant dark coffee and spill that over it. Wait for it to dry then singe the edges and the middle of the paper. Rip holes in the middle (like you're making a pape snowflake) and rub charcoal or coal all over your hands, then rub this around the holes. Wash your hands after! Then screw up the paper repeatedly and hey presto, you have the perfect old sheet. All the stuff will make it very fine paper, so be careful with it!

Just guessing - try on other paper (with same type writing on it) before you try with you homework. Use flame to singe the edges - quickly light and blow it out as soon as it is lit. Be ready to put in sink/water in case it goes up in flames quickly. Get a shallow pan/cookie sheet with edge. Soak in colored water, vinegar or something to tint the paper. Dry - perhaps use an iron to help the drying process - but put something between paper and iron like a thin cloth or sheet.

hmm i had a history assignment like this too i dont really know how to make it tan but what you can do is crmple it up, open it, and crumple it up again, then open it and burn off the sides or corners (not a lot just a little bit

put lemon juice on it, then put it into a preheated oven for 5 minutes then take it out and burn the edges a little :D works a charm!

Sprinkle it with tea or coffee then let it dry. I tried burning the edges but that can go really bad if you are not careful.

rub a wet teabag on it for the colour and burn around the edges