Tomato and chilli planting for beginners?

It is too late to start from seed and expect to get production even in the south. Depending on where you live you may be able to plant starter plants. Your container is too small for both. Call your County agent and ask for a vegetable planting guide for your region. It is free and will tell you when too start seeds indoors and when to plant outside. It will also give you information on spacing. I would hate to see you fail in your first adventure in gardening because you planted at the wrong time.

Welcome to the world of dirt therapy.

You can get smaller varieties of tomatoes more suitable to grow in a pot, if you choose a normal one that grows 6 foot high you will need to stake it.

I wouldn't worry about buying mulch- if you don't mind the look of it you can use shredded paper if you really want to mulch it.

You only have the plants indoors if it cold outside, tomatoes and chilli don't like frosts, if you are already half way through summer get them outside in the sun as soon as possible.

too late in the year for both plant radishes now, a 30 inch pot can take one tomato and one pepper, cages and stakes keep the tomatoes off the ground and help keep them from rotting

Plant them deeper next time.