Hi @abhieonweb, welcome on CodeChef
My opinion is, that entering beginner section and sorting problems by number of “Successful Submission” descending (click on link in table header) is the best place to start. It simply means that those problems are the easiest one. I’m not a newbie (I participated in more than 100 contests on TopCoder), but I’m using this approach in long contest and short contest here on CodeChef too
I believe, that if you solve first 10 problems, probably you will solve at least one in CodeChef long contest.
I believe that these 4 problems are most important  you will learm a lot about CodeChef environment

TEST, according to its name, it’s not a real problem, you just have to try to submit really easy problem

INTEST, this problem shows you, that in real life enornmous is something else (1TB big disk is almost standard today), but to read 2.5MB in 1 second can be a problem for some languages (Java, python and also C++ if you use cin/cout)

TSORT, it tests you if you know how to use sorting in your language, typically it can be done in O(n\log(n)) time, if try to implement your own it will cost some effort, on the other hand it’s not good idea to implement such well known algorithms, use one your language supports
 finnaly FCTRL2, that shows you, that in some problems you need numbers bigger than you normally use (int, long long, long double, …)

ATM is really trivial one, but a lot of coders had problem with that one  it is the second one ordered by “Successful Submission”, but “Accuracy” is actually 23.31%, in top 20 there is just one with lower accuracy FCTRL2.
Later when you have some skills, you don’t need to solve problems one by one, read few and try those you like the most Later when you will try some contest (I really recomment long contest, there are 10 days for 10 problems, but maybe you will solve 1 or 2 in your first contest, you have 5 days for each and typically there are some super easy), than read tutorial and try to solve at least 3 or 4 with tutorial help.