You need to make a choice between static and dynamic linking:
The advantage of dynamic links is that if you move the search page, the link URL is updated automatically. however, in your case using static links is not so bad if the search page is never going to be moved or unpublished (which seems likely to be the case) - especially if there are many navigation items to this search page that are rendered on all pages - static links will be much less of a performance hit.
If you want to use dynamic linking, you then need to choose between Page and Component linking.
With a Page link (<tridion:PageLink/>
) you link to your search page by passing the TCM URI of the search page in Tridion in the PageUri
attribute. You can put your additional query string parameters in the Parameters
attribute. See the online docs [login required] for all attributes
With a Component link (<tridion:ComponentLink/>
)you link to a Component on your search page by passing the TCM URI of the component in Tridion in the ComponentUri
attribute. There is no Parameters attribute, so for your requirement you would need to create your own extended Component Link control to add one - and there is this exact example here