I assume your loop is more than just one step. You should use the 'Loop Options' for a single step.
For looping on a group of steps, you can place them all in a sub sequence and then set the 'Loop Options' for the 'SequenceCall' step to set up your looping conditions. Pass values to and from the sub-sequence by Parameters.
You can keep the loop inline with the rest of your sequence by using 'Goto' or using 'Goto destination' in the Post Actions tab of the condition step.
Using a sub sequence will keep it easier to read and maintain.