You can search for sequences within a selected portion of your design by combining the "select" and "search" features.
Select the sequence
First you will need to select the portion of the sequence you would like to search within. Either click and drag a portion of the sequence or use the select tool.
More details on that here.
Search the sequence
Next, use the search feature to search within the selection by choosing the "in selection" option within the search feature.
