You can pack them together fairly closely. Succulents don't mind being a bit crowded. Water them when the soil is dry. Make sure there is good drainage in the soil and a hole in the bottom of the pot so the roots don't rot out. Finally, don't feel too bad if you kill a couple. It takes time to figure it out!

Only water when the soil is dry at least an inch deep. When you do water, water thoroughly, until water is freely coming from the drainage holes in the bottom. An optional way to water thoroughly is to let the plant pot stand in a tray of water for half an hourish (I use an inch or so of water). This is called "bottom up watering"

Make sure that any pot you use has drainage holes. A common mistake beginners make is to plant directly into decorative pots that have no drainage holes. This is bad because when the soil doesn't have enough chance to dry out between waterings, it leads to root rot. You can still use a pretty pot if you want, just make sure that you have an inner pot with drainage holes that you can take out of the exterior pot when it's watering time. (The decorative exterior pots can be useful for causing things to tip over less).

Finally, don't assume that succulents or cacti will be happy in bright, direct sun. They can still get scorched.

The ones in the bottom right even look like little asses.

Well, they are heavily edited for sure. Lithops aren't that bright. They survive by looking like rocks, not candy lmao.

But they are fun to grow (I have several)

I had some nice ones but my cat ate them. I suppose they feel really good to chew

It's badly etoliated (stretching to get more sun) and appears to be in a soil with too much organic matter.

The poor dear needs heaps more sun, and soil that doesn't retain much, if any water.

(I have a few lithops. I'm shocked yours is still alive!)