#1. You need to have a Garmin MapSource product. I will use MapSource US TOPO as an example.
#2. Install US TOPO on your computer.
#3. Install Trip & Waypoint Manager, which should have come with your 76Cx, along with a USB cord. Software installs required USB drivers.
#4. Test the link between your gps and your PC. Connect the Mini USB connection to the mini connection on the back of you gps. (Use care the rubber cover may come lose. If it does remove the retaining screw with a small screwdriver, and replace.) Have MapSource on the desktop, power up your gps. At the top of the tool bar there is the Utilities option, click, and then select Get Unit ID. Your unit ID# should show up.
#5. If you want to select Maps of your State you need to have US Topo-East CD in the drive and selected. Next go across the Tool Bar to the right of the up and down gps units. Using your pointer on the next multi-sided symbol. It is the map tool. Click on the map tool. Next move the right and click on the magnify glass. This is used to zoom in and out of your map. I prefer to use the mileage scale on the tool bar. In this case click on it and select 50 mi. Next select the hand symbol on the tool bar. Drop down on the map and drag the map around to an area of interest. If your are interested in your whole state you might start on the westside and work eastward. You will notice that the map is broken up by gray lines that represent Topo Maps Click on the Map Tool and bring it down to a map. Click on the Map and the selected Map will show in Pink. On the left side of your MapSource screen you will you will see the data tabs which will keep track of your Waypoints, Routes, Tracks, and Maps. At the bottom it will show how many you have loaded and how much memory each used.
#6. Waypoints. There are two ways of creating waypoints. Under the EDIT option in the tool bar you can select New Waypoint, or you can select the Waypoint Tool on the Tool bar. In most cases the Waypoint tool is the way go, except when you already have a Lat/Long. Then you can use the New Waypoint option under Edit, and enter your data.
#7. Once you have created a Map Set select File, Save As, My Documents, and create a New Folder, and name it 76Cx Map sets. Save your Map set. Pack a lunch if your are filling up a 1GB card. And save your invested time by saving your work product. You can always modify your saved map sets.
#8. With your powered up gps connected to your computer select the down arrow gps in the tool bar. A Send to Device screen will appear. If it does not show your gps, click on Find Device. In the Device box it should show Garmin 76Cx.
You can then send the Maps to your device.
Be aware that if you modify your map set at a later time and send it to your gps it will remove the one on the gps. It is better to modify your current map set on the desktop and then save it as a new file. After saving it load it on your gps.
Funny I have repeated this operation numerous times and I just ran into a bug, it maybe because I loaded the new Beta update.