If you have a lot of "instances" and you want show their on map, you will helped OS CCK. There are two ways to create location map - via the menu item with CCK manager and from CCK module. In this article we write about first step. For showing all you "instances" on the map you definitely need to use "location map field". How to create location map field on CCK see here.
To show all your instances on the map, we use basic layout - all instances layout. For example, we need to show all our "bookmarket" on a map. First of all we created "All Instance layout"(how created "all instances layout" on CCK see here.). Then we add the field with name "all-instance map".
Also on the right side of this option you can see the "form" block, where you can select "Number of displayed instances" and "How many items per page will be displayed".
The next step - is to create "show instance layouts" for showings "location map". We don't need to add any fields, because all we need is a place to "location map"
Then we go to our "all instance layout" and add "Attach layouts" - with name "Show book market on Map"
At this stage our work is over, now you can go to the frontend of the site and see the result.
There's also a second way to show your instances on map by using CCK module, please read here.