Hi and welcome to the Workshop of Glory! Here are a few quick tips to help you.

Uploading Levels
There are 2 buttons:
"Upload": this will upload a new level and update an existing level.
"Upload as New": this will create a new copy of your level. Use with care because this creates duplicates in the Workshop.

Creating Levels
If you want to get your level played by lots of people and rated well, make sure it can actually be completed. Play through it from start to finish and make sure it can be completed by all of the Vehicle Classses that you assigned.

It's also helpful to put in your description a rough difficulty rating: easy, medium, hard, etc.

Complexity Limit
At the top of the Level Editor is a long, yellow bar. This is the Complexity Limit Meter. Each object you add will fill it up a little bit more. More complex items will add more to the bar. Try to pay attention to the bar as you build/plan your level.

As development continues I should be able to raise the limit further.

Respawn Points
As you place Checkpoints in your level, at the bottom-left corner of the Level Editor screen you will see small circle icons with numbers. These represent Checkpoints. You can click any of these to temporarily change the respawn point for quickly play-testing your level.

Those are the basics! Have fun