Some of the standard fonts in Windows 7 such as Times New Roman, Arial and Courier New have support for Hebrew (with at least basic pointing, if you need it). You /can/ insert Hebrew characters as follows:
a. go to Word->Insert tab->Symbols group->Symbol->More symbols...->Symbols tab
b. choose Arial or Times New Roman (say) in the Font dropdown
c. choose Hebrew in the Subset dropdown (if the font does not have Hebrew support, you wont' see that option in the dropdown)
d. Select each character you want to insert, and click Insert. To create a pointed character, insert the character first and the point character afterwards.
You should find that Word alters the direction of text in a helpful way when you are entering text in this way, but it can become very confusing when you have mixed LTR and RTL text.
Windows 7 does come with other Hebrew-specific fonts such as "David" and "Miriam" that you should be able to use from Word, but they are mostly "display fonts."
This is obviously a very basic approach. There are various ways you can make life easier for yourself, e.g.
a. go into Control Panel->Clock, Language and Region->Change Keyboards or Other input methods (or Control Panel->Region and Language->Keyboards and Languages, depending on which View you have of control panel).
b. click Change Keyboards... then Add...
c. look for Hebrew in the list and click on the cross to the left to expand the options
d. expand the Keyboard option and locate and check the keyboard you actually have or the closest match you can find
e. Click OK
f. Take note of the fact that there is a "Language Bar" tab. You may want to go back there later.
g. Click Apply
h. Start Word and create a new empty document. Then notice that somewhere down in your notification area, you will probably see a language icon with a two-letter language code (e.g. EN). Click that, and select HE. Now, when you type on the keyboard, Hebrew
characters should be entered.
If you don't know the Hebrew keyboard layout, this is not terribly helpful. But you can then go to Windows->Start button->All Programs->Accessories->Ease of Access->On-screen keyboard. Again, I cannot be sure that that is available to you, but if it is,
click on it. Then arrange Word and the keyboard so you can see your document and the keyboard, preferably without overlapping. Then, when the insertion point is in Word and the HE language is selected in the Language "bar", the keycaps for the Hebrew keyboard
should be shown, and you can type using that keyboard. I don't know how you do pointed characters using that.
In addition, once the language is installed in Windows, you /should/ see some additional options in Word, for example in the Home tab, Paragraph group, there's an icon to switchthe text direction, stuff like that.
AFAIK you only need a language pack if you need proofing, and the appropriate Language Interface Pack (I forget what these are called in this combination of Windows/Office) if you want your menus etc. to be in Hebrew.