accessing the command prompt

[MICHAEL WEAVER]

Hi!
I am new to this list.
I am thinking of Running linux, and I have read that  Ubuntu seems popular 
so I am thinking of going for that distro and it was one recommended by 
someone I knew from a School I went to in Worcester. I am hoping to install 
it when I have chance to find someone to help me install it as I will need 
Sighted assistance because I am Totally Blind.
However the people who may be helping me install it have little knowledge of 
Linux. My sister offered to help me install it on my new laptop and my dad 
said he would like to learn about Linux after I have met and talked to 
people at my local Linux User Group. I was going to ask someone from my LUG 
to help me install it but it could have taken 45 minutes to do it and I 
didn't have a wireless card in my laptop although there is a slot for one.
If someone helps me install Ubuntu, how do I get to a command prompt before 
I type sudo apt-get install gnopernicus? I may need to instruct my dad or my 
sister as to how to get to a text prompt. Is it an ALT plus function key or 
is that for just switching consols?