Labmatrix is a web-based application, and is accessible at the URL https://labmatrix.nci.nih.gov/labmatrix/. Of note, you must use the Firefox web browser, specifically version 45 ESR, in order to access Labmatrix; if you don't have Firefox (or this version) on your computer, you can put in a help desk ticket to have it installed for you. Your login credentials are your central NIH username and password.
Manuals for Labmatrix can be found inside Labmatrix by using the Help link at the upper right, or on the Labmatrix Manuals page (http://go.usa.gov/YPW).
Accessing Labmatrix if you don't have the correct Firefox version on your computer
There are two ways you can access Labmatrix without having Firefox locally-installed on your computer, one if you're on a Windows machine and one if you're on a Mac.
If you are importing clinical labs or cultures, you'll also be using the Labmatrix Lab Loader web application, which lives at https://lmlabs.cancer.gov/; your account information is again the same as your NIH username and password.