Pretty simple to use - you have a channel selector (Channel 16 is always the emergency channel and should ONLY be used for actual emergencies, it is monitored by the USCG) and then your other channels will be assigned
In most areas recreational anglers will use certain frequencies to communicate between boats, commercial boats other channels, etc.
Here is a list:
https://navcen.uscg.gov/?pageName=mtVhf
As far as operation - you have your volume, your squelch (which makes the radio more or less sensitive) and your transmission control device (the part you speak into!)
Using a VHF radio is one of the easier things to do on a boat, but their are things you need to do to operate a VHF properly. Most VHF radios have some or all of the following:
Volume Knob
"Squelch" Knob - Adjusting the squelch is similar to tuning your radio--it will make the signal sound
much more clear.
Channel Knob or Up/Down Buttons - This lets you change the channel you are using.
Channel Display Screen - This tells you what channel you are on, and also any other feature that you
may be using.
Weather Button - This is a direct way to get to your local weather channels.
Scan Button - This will automatically change your radio channel to one that is currently being used by other boaters. You may also be able to "Priority scan" which will allow you to program specific channels that you frequently use.
16/9 Button - Automatically takes you to either channel 16 or 9.
1/25 or Hi/Lo Button - This allows you to raise or lower the power with which you broadcast your signal. For boats close to you, use low power. For boats farther away, use high.
INT/USA - Allows you to change channel type if you leave the United States for other countries such as Canada.
Transmit Button - This is usually on the mike. Simply push it down, and your radio will transmit a signal.
A few other things:
All VHF radios operate at the same power - the distance you can transmit and receive is controlled by the height (and size) of your antenna - lots of stuff on the web about this
Learn how to properly use the radio - it is NOT a CB radio so you only use a few :radio" speak words. Over when you are done speaking but the communication is not ended, Out when ended, Roger to show you understand, etc.
Also - know the difference between a MayDay and a Pan Pan
Mayday means that immediate danger of loss of life or serious harm
Pan Pan is used when you have a none life threatening emergency - for example the boat will not run and you are stranded.
Know your phonetic alphabet:
A Alpha
B Bravo
C Charlie
D Delta
E Echo
F Foxtrot
G Golf
H Hotel
I India
J Juliet
K Kilo
L Lima
M Mike
N November
O Oscar
P Papa
Q Quebec
R Romeo
S Sierra
T Tango
U Uniform
V Victor
W Whiskey
X X-ray
Y Yankee
Z Zulu
Finally - I strongly suggest you invest in a subscription to BoatUS or a similar service