Awwww how cute!

Emily, with our rats we made a cardboard run.
Get some boxes from a store, preferably the ones with the shiny print on them, not regular coardboard, take them apart and then tape them together like a puppy pen.
Put toys in there and watch the mice have fun.
They can't climb up the sides of the slippery boxes and if you make it high enough they won't just jump out. You do have to keep a close eye on them though just in case.

Hammocks are fun toys and beds. If you have a solid lid for the tank you can sew a bit of string onto one side of a sock and hang it in the tank, they love snuggling up inside them.
With mine I cut up an old towel and attached it to the top of the cage... you would have to wait until they are in a proper mouse cage for that though.

Hidey holes and sleeping boxes can be just small cardboard boxes with an opening cut in them. I'll never buy plastic or any other kind of box because they love chewing on them and they are easy to replace.

Your mice are adorable! Mice are very intelligent, and have very distinct, different personalities.

A sterilite storage bin is good for small mice. You need shredded newspaper or some type of bedding to cover the bottom of the bin. It should be deep enough so they can burrow under it. You will need to change the bedding at least once a week.
In the bin/cage, you need several cubbies - hiding places. Old margarine tubs, clean tin cans, small boxes all work nicely. Mice like to hide, so give them plenty of hidey places.
You also need fun things for them. Tape several toilet paper rolls together (3 on the bottom, 2 on the next row, 1 on top - like a pyramid) so they can climb in and out and over. Another fun thing is to stack several cardboard drink carriers. You really should invest in a wheel. Mice are active little things so give them plenty of fun things.
Feeding - As mentioned, make sure you have a water bottle with a spout. Make sure they always have fresh water; you will need to give them fresh water every day. As for food - mice really don't like cheese. A good granola-type cereal is good. They like oats (not instant) most any vegetable, pasta, nuts and seeds. Whatever you have for supper, they will probably like. They like grapes and bits of carrot or apple.
Mice are very sweet. Try to handle them some every day, but if you miss a day, they will be all right.
As mentioned by others, boy parts show up pretty quickly. You don't want males and females together, and if you have two males you will probably have to keep them separated or they will fight. Females get along together just fine.
Enjoy them. I had mice for a number of years and loved every one of them.