Minecraft – How to set a spawn point upon death

You can always use a command block with the following setup:

Replace <name> with your name, obviously.

If you want to do this with all users on a single world, use the following command:

/spawnpoint @a

Make sure you turn off command block output, though, and also make sure you put this block in a permanently loaded chunk (your spawn chunks, for example). You may wish to use a setup involving repeaters instead of a repeating command block (as repeating command blocks act very quickly, and may cause lag). I'd generally suggest against doing this, however, because you don't prevent yourself from dying in a loop (which is not only possible, but probable in this).

If you are using a button/pressure plate to toggle the command block then set the options to
Impulse Unconditional Needs redstone

If it is being executed after another command block it needs to be set to
Chain Conditional Always Active

Your command: /tp @a[team=(team name)] <x> <y> <z> uses the proper target selector.

It sounds like you are new to command blocks. I highly recommend you visit the wiki pages for commands and command blocks, they contain lots of valuable information. I reference them a lot when building various command block creations.