VNAV SELECTION AND OPERATION

[ctmcewan]

Hello,

Can you please advise how I enable VNAV how I know it's enabled and what criteria I have to observe to make VNAV work.

As explanation I construct the flt plan, adding w/points and select and put in altitudes for each leading to final destination, after selecting the initial cruise altitude do you need to adjust altitudes as each way point reached or is approaching?.Do I need altitude hold activated in these cases.

Thanks