Regardless of the software you use to do it (audacity will do just fine) there are a few things you need to think about.
When we record a voice over a microphone we're not just picking up the voice. There are a couple of other things we pick up too.
The walls of the room will have some reflective qualities that will add the smallest touch of short-tail reverb. There are plenty of free reverb plugins that will mimic 'studios' or 'rooms' - a little will go a long way here so be gentle with it!
We also pick up other things that are going on it the room - This is known as 'room tone' or 'wild track'. this will contain all sort of things like aircon/heating/other machinery running in the background very quietly. Some free sounds libraries have room tones to download. Again, a little will go a long way so go easy.
Finally, we need to look at post processing - What was your voice recorded for and how is it going to be used? There are lots of things you can do here with eq, saturation, compression, etc. For example, If this is a radio presenter's voice, you could shave a little off of the high end and add some compression to get that intimate radio voice sound. If it's a vintage tape recording then you could drop off the low end and run it through a little saturation, a vintage crystal mic will have very little low end and plenty of saturation where a more modern large diaphragm mic will capture everything...
Try listening to the sound you want to mimic and try to understand how it's different to your recording.