Create an Unformatted Text Part with a call to the desired version of jquery.  In the Advanced Options, select "In the <head> tag" from the Placement in HTML drop-down. 

Note that the jquery call itself is outside of Blackbaud's Scope of Support for Blackbaud NetCommunity. 

Please contact the appropriate software vendor or IT professional for assistance with this process or issue, which is beyond Blackbaud's scope of support.