Model Builder - Integrating Select by Location and Buffer

So I'm trying to create a model tool in ArcGIS 10.1 that will integrate select by location and buffer.

These are the features that the user is supposed to be able to choose:

Select Layer by Location - selecting features

Buffer - distance of buffer radius (must be in km)

These are the features that the users will not be able to change:

Select Layer by Location - Relationship (COMPLETELY_WITHIN), Input Feature Layer

Buffer - Dissolve type (LIST), End type (ROUND), Side type (FULL)

This is the model I have created so far, but it doesn't let me enter all the fields I would like to enter, and when I run it it generates no output:

How do I create a model where I can enter the values I'd like?