Hi Shanti,
Shift register is somewhat like a local variable in C++. It's used to
save values from one iteration of the loop to the next. Please search
for "Shift registers" in LabVIEW help (Help->Search the LabVIEW
Help) for more information regarding shift registers.
Sequence structures allows you to execute different VI's in sequence. Further information is also available in LabVIEW Help.
Like Kenny mentioned, there are a lot of shipping examples that utilize these functions, and there's also a lot of resources online.
You can find the examples in LabVIEW, go to Help->Find Examples, or use the template by go to File->New...->VI->From Template->Frameworks->Design Patterns, or find more examples at www.ni.com/devzone.
Hope this information helps.
Yi Yan
Applications Engineer
www.ni.com/support