Any suggestions for best resources/websites to learn about the most common computer programs used in civil/environmental engineering?

The computer programs will vary depending on the university/college, course, and company you work for. I recommend learning how to use Microsoft Excel since it is one of the most common programs used and it also functions as a place to store datasets that connect to other programs. Another common program used especially for generating charts, figures, and calculating statistics for your data sets is R. This is a free program and there are lots of resources online in forums and on youtube that provide guidance on how to use it. Another program that is common in civil engineering design is AutoCAD. I believe you can access this program for free as a student through the Autodesk website. There are guides and resources online for learning how to use AutoCAD and many civil engineering college curricula include an instructional course on how to use AutoCAD. These 3 programs are a good starting point to explore. You can also reach out to your community college or colleges you're interested in attending to find out what programs they use and if they have any classes available that you can take. Many community colleges and universities have online course options available to learn these programs.

As someone who is inclined in the "Design and Build" part of engineering our top most used programs here specifically in my place of work are 
Planning stage: Autocad, Sketch up, Revit, Photoshop 
Design stage: Staad, GRASP, Excel.

For websites on a budget, that could teach you the basics you can't go wrong with Youtube. This was my first teacher when I wanted to learn rendering.