d4 dude D4
e4 c5 what do I do now

Well I'm not a master or even any good for that matter, but I assume it's to get control of the e5 and d5 square.
You could try looking at sample games in books like My First Chess Opening Repertoire for White
https://www.newinchess.com/media/wysiwyg/product_pdf/9033.pdf
https://chessbookreviews.wordpress.com/tag/vincent-moret/
and Opening Repertoire 1 e4.
https://www.newinchess.com/media/wysiwyg/product_pdf/7819.pdf
"... There is no doubt in my mind that if you really want to test the Sicilian then you have to play the main lines of the Open Sicilian. The problem is that there are just so many of them ... and keeping up with developments in all of them is a substantial task. ... as you become older, with other demands on your time (family, job, etc.) then it becomes more and more difficult to keep up with everything. At this stage it may make sense to reduce your theoretical overhead by adopting one of the 'lesser' lines against the Sicilian: 2 c3, or the Closed Sicilian, or lines with Bb5. ..." - GM John Nunn in part of a 2005 book where he discussed a 1994 game in which he had played 2 c3.
"... There is no doubt in my mind that if you really want to test the Sicilian then you have to play the main lines of the Open Sicilian. The problem is that there are just so many of them ... and keeping up with developments in all of them is a substantial task. ... as you become older, with other demands on your time (family, job, etc.) then it becomes more and more difficult to keep up with everything. At this stage it may make sense to reduce your theoretical overhead by adopting one of the 'lesser' lines against the Sicilian: 2 c3, or the Closed Sicilian, or lines with Bb5. ..." - GM John Nunn in part of a 2005 book where he discussed a 1994 game in which he had played 2 c3.
When you develop an opening system, it becomes intrinsic to oneself after various repetitions
e4 c5 what do I do now