How do I watch the replays? I only get the error "Unable to load map".

You need to get the exact same map version to watch the replay. Get the current ladder maps here.

How Do I get on bot on the ladder?

Compile you code into either a executable file or a command center config file. Then either upload through your profile, or add a download link.
The format should be similar to the way the sc2api examples are structured. You should follow This example as for how to connect to the LadderManager software
If you are just starting here you can find a guide explaining how to start with a generic bot you can use as starting point (recommanded). If you instead want to start with a blank bot use this guide. Once you register your bot, it will need to be verified to check for crashes etc. and will be entered into the ladder as soon as possible.

Can I update my bot?

Yes. A continuous ELO rating is used to encourage well rounded bots and not "one trick ponies".

Can I watch bot matches without loading the replay file?

The bot matches get streamed occasionally on If the stream is offline check out the videos section.