You need to prepare a few pieces of information before you start.
1) Your geiger counter model and the type of tube inside it
2) The conversion factor for your tube. This is a number that converts CPM into uSV/hr. For the SBM-20 it is 0.0057
3) The decimal format latitude and longitude of your location. Go to Google Maps, go to where you want the marker to be positioned, right click and select 'What's here?'. The info window that pops up gives you the coordinates. Latitude, longitude.
4) The password you want to use to send data. This data is sent unencrypted to support simple and homebuilt geiger counters, so use something unique but unimportant.
5) The warning and alert levels in CPM. For the SBM-20 that would be 50 and 100 respectively. For a more sensitive tube, perhaps 100 and 200. For an alpha detecting pancake perhaps 250 and 400.
Upon successful registration, an email will be sent to you. Click on the link to activate your account.
Log in, then click on 'Profile' at the top and double check your information. You can change your profile by clicking the 'Edit Profile' button on the right hand side. Turn off alerts while you set up!
Enter your username and data sending password into the software you use to send data. Then, configure the software to work with your geiger counter. Consult the forums for how to do this with your particular type of geiger counter.