Welcome aboard.
Start here – Beginner questions - Support - Xert Community Forum (xertonline.com)
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You need enough data on file for XATA (Xert Adaptive Training Advisor) to recognize patterns in your current training. If you don’t have that from syncing Strava or Garmin Connect activities you will need to ride for a few weeks to build your data profile.
Pacer needle is tied to your ramp rate (IR = improvement rate) and weekly hours you are willing to commit to. You want to strive to keep the needle in the 11am-1pm range to stay on target for the week. XATA calculates the weighted average load based on a rolling seven day period.
Triangle color represents predicted form 24 hours from now while Status Stars color at top of the page indicates current form. Status stars count indicates training load level achieved.
There are numerous (?) icons and hyperlinked text you can click on for help tips…
Example: Xert Training Pacer – Xert (baronbiosys.com)
There are many more newbie tips in the thread linked above including a link to the beginners guide. I suggest you read through that first as you begin your journey on Xert.
There is also a link to new series of YT videos that explain the concepts…
Yes, there is a learning curve to Xert but it will all make sense over time as you settle into a new way to train by power. More questions? Ask away. 
Reference –
Training Status and Form – Xert (baronbiosys.com)
Training with the Xert Adaptive Training Advisor – Xert (baronbiosys.com)