I suspect the confusion is because the tutorial code samples are not done in the wake of a bower-based installation. I used bower and everything you need to include in your HTML (i.e. the Javascript and CSS files) are all dropped in bower_components/angular-ui-grid:
matt@RD0123:~/$ ls -lt bower_components/angular-ui-grid
-rw-rw-r-- 1 matt matt 704 Aug 26 10:43 bower.json
drwxrwxr-x 17 matt matt 4096 Aug 26 10:43 less
-rw-rw-r-- 1 matt matt 726 Aug 26 10:43 package.json
-rw-rw-r-- 1 matt matt 2047 Aug 26 10:43 README.md
-rw-rw-r-- 1 matt matt 53493 Aug 26 10:43 ui-grid.css
-rw-rw-r-- 1 matt matt 8728 Aug 26 10:43 ui-grid.eot
-rw-rw-r-- 1 matt matt 1019595 Aug 26 10:43 ui-grid.js
-rw-rw-r-- 1 matt matt 39326 Aug 26 10:43 ui-grid.min.css
-rw-rw-r-- 1 matt matt 284080 Aug 26 10:43 ui-grid.min.js
-rw-rw-r-- 1 matt matt 9065 Aug 26 10:43 ui-grid.svg
-rw-rw-r-- 1 matt matt 8564 Aug 26 10:43 ui-grid.ttf
-rw-rw-r-- 1 matt matt 4792 Aug 26 10:43 ui-grid.woff
Then, assuming your HTML file is located in the same place you did the 'bower install' from, you could just relative-reference them thusly:
<link href="bower_components/angular-ui-grid/ui-grid.css" rel="stylesheet" />
<script src="bower_components/angular-ui-grid/ui-grid.js"></script>