There are two main ways to visit a user’s profile. 

From Spiral top menu:
Click on “Spiral” icon on the bottom menu;
Locate the magnifying glass icon on the top right corner and click on it;
Type the username or name of the user and select the profile from the shown list to be redirected to his/her profile.

From Spiral feed:
While scrolling on Spiral feed and getting interested in one user’s post, click on the username and you will be redirected to the user’s profile.