You can use a specific Outbound Caller Name for all calls you place from your dialer. Just head over to your 'Account' page:
And look for the 'Outbound Caller Name' field.
Here you can type any word or phrase that you want to deliver as the Caller Name. Please note that this will affect all your calls, and it's not possible to set a specific Caller Name for a specific Number.
In case you want to change the Outbound Caller ID (that is, the Phone Number and not the Caller Name that you deliver), check out this article.
Remember ! It is up to the carriers that handle the calls to actually deliver the Caller Name that you set, and sometimes they reject them. Unfortunately we don't have control over that, but be assured that we will always make the best effort to try and deliver it.