Making a GRAPHIC or IMAGE a link
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Click on the graphic.  Next click on Insert and select Link.  Now type the URL  or the file name for another one of your pages and click OK.
Note:  To make it easier on yourself, go to the site where you'd like to link and highlight the URL.  Do an Edit - Copy.  In the "Link to page or local file" box Paste the URL and then click OK.  Once a graphic is a link the select arrow will become a hand when brought across the image.

Making a WORD, SENTENCE, or PHRASE a link
Highlight the WORD, SENTENCE, or PHRASE and once again click on Insert and Link.  Type the name of the file or the URL to where it is going. e.g Click Here to see an example.   is the sentence which in this case will take you to the main Beta Page.
 

Words or graphics can be made into links in tables too.

Here is what the HELP section in Composer has to say.

Linking Within the Same Page To link within the same page, create a target, then create a link that points to the target.  1.Put the cursor at the beginning of a line     where you want to create a target, or     select some text at the beginning of a     line.   2.Open the Insert menu and choose Target.  3.Type a name for the target in the edit box     (up to 30 characters). If you selected     some text in step 1, this box already     contains a name.   4.Click OK. A Target icon (visible only in the     Composer window) appears in your     document to mark the target's location.      Note: Targets are also called anchors.  5.Put the cursor on the text or image that     you want to link to the target.   6.Open the Insert menu and choose Link.   7.Open the File menu and choose Browse     Page; then click the link you just created.

Linking to Other Pages You can link to local pages on your own computer or on your workplace's network, or to remote pages somewhere on the Internet. You can quickly create a link by dragging and dropping from other windows (Mac OS and Windows only). For example, you can highlight a link from a web page, bookmark, or mail and news window and drag and drop it on your page. You can also create a link using the Link Properties dialog box:  1.Select the text or image you want to link to     another page.   2.Open the Insert menu and choose Link.   3.Use the Link Properties dialog box to set     up the link. The dialog box is explained     below.      About the Link Properties Dialog Box Use this dialog box to insert a new link or modify an existing link. Link source Enter the text you want link to another page or target. If you've already highlighted an image or text, you see it here. Link to page location or local file Type the local path and filename or remote URL of the page you want to link to. If you're not sure of the path and filename or a local file, click Browse to find it on your hard disk or network. Show targets in Click Current File to see the named targets in the page you're currently editing. Click Selected File to see named targets in the file you specified under "Link to page location or file," above. Select a named target (optional) The targets you see listed here depend on what you chose under "Show targets in," above. Targets (also known as anchors) are specific locations in a page. (You can create targets.) If you want to link to a target, select one from the list. Remove Link Click to unlink the selected linked text. If the current selection contains more than one link, an alert box appears asking you whether to remove all links. Extra HTML Displays a dialog box where users familiar with HTML and JavaScript can add tags that further define the table. To preview your settings, click Apply. To accept the changes, click OK.

Linking to Images You can make images behave as links in your pages. When the user clicks a linked image, the browser window displays the page that the image is linked to.  1.Click to highlight an image on your page.  2.Open the Insert menu and choose Link.  3.Use the Link Properties dialog box to set     up the link. Tip: Dragging a linked image from the Navigator window into a Composer window copies both the image and the link.