We don't do soil testing here at our office but you're welcome to stop by and get a soil test kit to send it up to CSU. Alternately you can go to: http://www.soiltestinglab.colostate.edu/documents/soilsample_horticulture.pdf and print this form out to mail in to the CSU soil test lab. You can put your sample in a ziplock bag and mail it with the completed form. To take a good sample take several samples a few inches deep around the area you are interested in. Mix all of the samples together and let them dry out of the sun before sending them off. You probably won't need all of it, you don't need to fill a zip lock bag or one of our test kit tubes to get good results.
Let me know if you have any other questions!
Also for soil amendment please see our very useful fact sheet on the subject: http://extension.colostate.edu/docs/pubs/garden/07235.pdf.