Once you have a channel, you can move to the project's Editing Screen to upload. Select the project you want to upload from the Home Screen and move to the Editing Screen.
If the rendering is already complete, you will see the YouTube button on the top side (if the project hasn't been rendered yet, click the Download button on the top side and perform rendering first). Press the YouTube button.
Now you can set the title and description of the video you want to upload to YouTube. After crafting your content, press the YouTube button at the bottom right to complete the upload.