Welcome to our community.
To get a solution as fast as possible we recommend you always do a search on our website for the error message you get before posting a new question. This might help you find the solution in minutes instead of waiting for our next-day answer.
For example, in your case the solution seems to be the one described in this older post, It is a very easy small mistake with new users:
If this old thread doesn't help you please follow the recommendations from this page
when making a new post. It will allow our team to give you a faster answer.