How do I tighten the bolts that hold my toilet in place?

One is more likely corroded/rusted in place. The loose one slipped out of the flange. You may need to cut them out with a hack saw/blade. Replace the wax ring and install new bolts.

http://homeguides.sfgate.com/replace-toilet-anchor-bolts-21372.html

Liquid wrench might help

Are you talking about the toilet seat? You use a screw driver on the top of the bolt, and then either hand loosen the nut underneath, or use a pair of plyers to loosen the nut.

Spanner?

this is a common problem and you can fix it a few ways but I will only tell you how to repair it to original condition. Use a cutting wheel on a dremel tool to cut the old bolts off. Shut off the water and remove the waterline. Drain the tank. Lift the toilet and ( while wearing rubber gloves) remove the wax ring. Remove the bolts and inspect the flange if there‘s damage buy a new wax ring and bolt kit and reinstall. If there is damage take a few pictures and show the hardware store person for advice.

I tried that, didn’t work. Someone told me i’d Have to somehow cut the bolts and reinstall the toilet.

no, I referr to the bolts that hold the toilet in place on the floor.

Tthe I had about the same situation. I sprayed WD40 on the nuts waited a bit and with a fair bit of muscle they came off. You can buy the replacement bolts and nuts as well as a new wax ring at hardware stores or Walmart. Anytime you have to replace those bolts and the toilet is lifted you need to replace the wax ring.