Note: If you have the bike upside down, DO NOT actuate the brake levers as this will push air into the calipers and will need a bleed to remove it. Also when replacing pads or removing the wheels, DO NOT actuate the lever as this could get the pistons in the caliper out of their location.
Here are a couple of quick video guides that provide guidance for adjusting hydraulic disc brakes.
And here is a quick video on replacing the pads.
There are many reasons why you might need to bleed your brakes. Remember before doing this to verify your brake pad wear.
You will need Bicycle Rated Mineral oil like Shimano or Tektro which can be easily bought online and a Bleeding Kit
Here we add the two best descriptions of how to do it
This is a quick 5 minute written tutorial from our friends at epicbleedsolutions.com
And here is a detailed video from Amstudio
If you have any questions please contact our techs at email@example.com
Attention: This is a guide to provide you with a reference for the task detailed. There are many instruction guides online that can help and also local bicycle repair shops that can perform this task. Always be Safe and test the result in a calm environment before going on a test ride