The first immediate problem is plugging your cellphone into your Windows® Laptop computer. Did I hit it? The connection from the cellphone is the "headphone or earpiece" signal, and likely to be powerful and closer to Line-Level and not Microphone Level. Briefly, you can't plug that into the Mic-In of your computer. You might be able to find Windows instructions that switch your one connection between Stereo Line-In and Mic-in, some computers have that. Many don't. Some computers have a blue Stereo Line-In in addition to the pink Mic-In. Use the blue one.
What's probably going to happen is you need an adapter device like a UCA-202.
http://kozco.com/tech/audacity/pix/UCA202.jpg
Next problem is recording your messages as one continuous sweep and not piled on top of each other.
-- You can listen to your existing messages with the Solo (by itself) and Mute (shut up) buttons to the left of each track.
--You can Pause Recording while you select the next message.
-- Audacity 1.3.13 has the ability to Append Recording. Full Stop and then pick up again where you left off.
If you're not in Audcity 1.3, you should be.
Audacity 1.2 is very old and no longer supported,
patched, corrected, or updated. Audacity 1.2 can
be unstable on newer computers.
Download and install the latest Audacity 1.3 from here...
http://audacityteam.org/download/
You can install both audacity 1.2 and Audacity 1.3 on
the same computer, but only use one at a time.
Audacity 1.2 will not open projects made on Audacity 1.3.
If you use MP3 or some of the more modern audio
compression formats, get Lame and FFMpeg software
from the same web site. Do not use older software
or software from other web sites, even though they
may have the same names.
Koz