Thank you so much for this! She's had a bath as the vet said she had mud stuck in her shell. Some of it has come out although we can't get all of it out. We've put her on newspaper and she is so feisty and just wants to keep moving so doesn't like being in a box but its only temporary.Hello and welcome!
1. There is a terrific long-read post on this forum: from Tom, one of the respected members There is all the necessary introductory information there. That's another useful long-read focused on temperate species, like russian tortoises. (link) It's overwhelming amount, read it little by a little.
2. Yes, it's a good idea to try to find owners first. Russian turtles are very good at escaping and do that all the time.
3. To get started, you definitely need some space for it - large plastic box (like christmas tree containers, cement mixing tub), old bookcase laid on it's bottom and such.
4. Using soil as substrate is not a good thing (unless you are 100% sure it's free of pecticides and fertilizers), but for couple of days it could be just a newspaper .
5. You will need good lightning and heating - Russian tortoises brumate in winter and that's not what you probably want right now. For a quick start it could be simple LED light (cold day light temperature, 6500K or about that) and incandescent bulb if you put tortoise box in your living space (where should not be too cold at night). UVB light could be added later on.
6. If you have some greens at home (lettuces, kale, endive and so), then you have some food. Probably she will refuse to eat (because of sudden changes and she might be getting ready to brumate) for some days.
7. To give a little "boost" to her health and condition - you might give her a bath. Pour lukewarm (comfortably warm) water in the plastic tub, container or large enough bowl - few centimeters or less. Water level should be a bit higher than tortoise "belly" (aka plastron). Than put tortoise in for 10-15 minutes (please, keep your eye, so water don't get too cold). After bath use paper towel to dry her up a little and put her back in the enclosure. If she drinks, pees or poops (in any order) - it's okay, they do it all the time.
When she's in a warm place, after "soaking", you can get yourself some tea and read the posts I mentioned in the beginning. Please keep us informed, and ask questions. Photos of tortoise are always welcome as well
If you decide to keep her - it would be really long-term commitment. Please, consider it carefully.
She could be stressed by being caught, changes in the environment and such. So she tries to do anything to escape. I think when left alone in the box with the lights out she will calm down (don't forget to put the lid!). So you'll have time to think what you have to make her a better temporary enclosure, what to use as lightning and heating and how not to waste a lots of money (don't rush to a pet shop).
