heya
1st youll need to decide what kind of tortoise youll want?
whetehr you want a good sized to a small one and whether youll want it to hibernate or not and what itll need to live.
Once youve chosen the species (also look at pics to help choose) google some care sheets (read a few though) and get started on getting some equipment together.
With small med species (which are good starters) like horsefields, greek spur thigh and hermans, mostly need a good sized indoor table, complete with a water bowl (not to deel but big enough to fit in) a feeding slate to put food on, substrate ( most people choose a 60/40 soil sand mixture as its most natural) a hide or 2 and plenty of large rocks.
for lighting you need a basking bulb at one side of the table to get a hot and cold gradient. with horsefields and hermans they need a 30-32c basking spot temp and a 100watt bulb can acheive this. Youll also need a dimming stat to moderate the temps so they dont flucuate. Also a uv bulb 10% is the lowest one but most use 12% and arcadia is a good brand to get.
They will also need and outdoor enclosure so they can get natural uv rays and this needs to be escape proof and covered over with some sort of mesh or netting that will let the suns rays in but no cats/dogs/birds.
Meds are also veges and thrive on our weeds such as dandelions, nasturtiums, panseys, clover, sow thistle, bindeweed, dead nettle, shepards purse (to name a few) no iceberg lettuce should be given and if any a leafy lettuce can be used just as a rocket and water cress. Shouldnt really give them fruit or veges either but some such as apple and strawberries can be given AS A TREAT bout once a month or so but nothing to citrus or acidic and not too often as it will upset their tummys and there poos wont be very pleasant (not that they were before) .
Hope all this helps