To get an address like yourname.tez as well as a custom URL for your profile, you must buy a tezos domain and set the reverse record to your address. You will need to go to this website: https://app.tezos.domains/
You can have a look at this video which explains in detail how to do it:
If you don’t have a tezos domain, your address will be a succession of letters and numbers like this (you can see the address ending by doY):
Note: you can buy a tez domain for someone else, and send it to them (through objkt or your wallet, click here to see how to send a piece). Ask them to set the reverse record to their address so that it is linked to their address.
If you get a tez domain, your address will appear like this (you can see cabline1.tez):
But what is the most interesting is that once you have a tezos domain, you can get a custom URL for your objkt profile!
Like this:
Please note: it is not possible to have a custom URL for your collection.