Api.GetSearch() method, you can pass the parameter
raw_query, which should be the query string you wish to use for the search omitting the leading "?". This will override every other parameter. Twitter's search parameters are quite complex, so if you have a need for a very particular search, you can find Twitter's documentation at https://dev.twitter.com/rest/public/search.
For example, if you want to search for only tweets containing the word "twitter", then you could do the following:
results = api.GetSearch( raw_query="q=twitter%20&result_type=recent&since=2014-07-19&count=100")
If you want to build a search query and you're not quite sure how it should look all put together, you can use Twitter's Advanced Search tool: https://twitter.com/search-advanced, and then use the part of search URL after the "?" to use for the Api, removing the