There are many fonts that are included with Microsoft Word and most may be suitable for your needs. However, in the font list, there are no bubble letters in which to choose. Thankfully, if you want the playful look of bubble letters, they are available off the Internet -- many for free -- and can be added to your font list for you to use whenever you'd like. You can even change the size and color and select bold, italics, highlights and underline as you would other standard fonts.
Download a bubble letter font from the Internet. There are many sites where you can download new fonts for free and some for a fee (see Resources). When you are on one of these sites, search the keyword "Bubble" and choose the style you prefer. Click the Download Now button and then choose Save when the File Download window pops up. Then you should select a file to store it in and a name the font.
Unzip your font. The font was probably downloaded onto your computer as a zip or compressed folder. Right-click on the folder and select Extract All.
Move your new font to your fonts folder. Click the Start Menu and choose Control Panel. Next, select Appearance and Personalization. From there, click Install and Remove Fonts. Once this window opens, right-click on a blank space near the list of fonts and select Install New Font. On the left, find where you saved your font and click Install Font on the top right of the window.
Open up Microsoft Word and click the down arrow next to the font list on the toolbar at the top to open up your fonts. Choose your new font which you named when you downloaded the file. Start typing. If you have already typed your document, then highlight the text and change the font. Change the style, color and size as desired.
You can also purchase a CD with fonts in which to install into your fonts folder.