Open header.php which can be found inside “wp-content/themes/dokan/” and go to line no. 69 and you'll see something like <div class="col-md-4 col-sm-5">.
Change that to <div class="col-md-4 col-sm-5 col-md-offset-4">. Here we have just added a class only. You may use col-md-offset-3 or col-md-offset-5 depending on the alignment you need.
The same applies for the menu. Go to line no. 89 on the same header.php and you'll see something like <div class="navbar-header"> and you'll have to change that to <div class="navbar-header col-md-offset-4">. You can use the value in col-md-offset from 1 to 12. The lesser value will drag it left and the higher value will push it to the right.