Sounds like you are new to LabVIEW. First, understand that it is not a simple tool like Microsoft Excel, but rather is a full-blown programming language. There are lots of resources for learning LabVIEW, and here is one:
Those 9 steps go over just the basics of LabVIEW. You could skip step 8, but the other 8 steps are all very fundamental, and if you don't know those 8 steps well you are not going to be able to do much in LabVIEW at all.
If you already know another programming language, like C, you will find it easy to learn LabVIEW as in most ways it is the same as any other programming language except it uses graphics rather than text. If you don't have any programming experience, you are really starting from scratch and need to learn the basics of programming structures, data structures, and logic.
Once you know LabVIEW in general, to get started using the U3 in LabVIEW follow the 6 steps here:
I am looking to acquire sensor data (voltage signal) using LabJack and use it in labVIEW programming. I would like to know if there is any specific icon in labVIEW to acquire the data using LabJack.
The simplest way to acquire a reading from an analog input is with a call to eAIN:
See "U3 eAIN Example.vi" to get started.
and also about setting the sampling rate for reading the data.
If you use stream mode, the sampling rate is dictated by hardware. If you use command-response mode the sampling rate is dictated by software:
We suggest you use command-response mode first, and move to stream mode later if you have to. Check out "U3 eAIN Loop with Chart.vi" for an example of software-paced acquisition.