Q) I have Created a new software using some Open source Packages, (Lets says , jQuery). Do I need to make this Open Source and give to public.
First of all, Open source has nothing to do with public. You never have any restriction to make your public. Its all about customer.
If you create a new Software with the help of Open Source Packages, then new Code which is written by you is your property. As long as you are using it for your home purpose Or your personal purpose, you needed to tell anybody in the world that you are doing this. This is totally legal. Also, there is difference is using Open Source Packages and modifying a OpenSource Packages.
Now, Let suppose you write Package A with Already existing Package O which is Open Source.
case 0 - You want to use it for your purpose.
Yes, you can do it. You need valid license which allow you to use the software. (of-course every software has it)
Case 1 - You want to sell it.
Yes, you can sell it, OpenSource means showing code and giving right to your customer. You can Give code and Software using CD Or USB drive. putting on web is not needed.
Case 2 - You want that anybody can use it without giving money,
Yes, you can do it, best way to do so, upload it on some website so that anybody can download it.
Now One more consideration that License of Packages O. You need to read about license. License contain 2 things
1) how and in what ways you can use a package
2) how and in what ways you can distribute a package. (with or without changes)
In above case 0 - you need to see the condition to use a package.
In above case1 and case 2 , you are see the condition to use and distribute a package. (you further needed to check, you are making changes in pakcage O or not)
If the terms and condition of "Package O" disallow to redistribute it, Then you must not bundle it, Tell your customer how they can Install the dependency.
Finally, what about license of Packages A, which you have created, It is your wish what license you want to put it. License of packages O has not control over it. you have full freedom to license your code in Open/Close licensing method.
Q) I do not want o give source code to my users/customer
Then your package will not become OpenSource. In Open source you basically license customer to modify or reuse a code. if you do not provide code then your customer can put in court for giving damaged product. What you can do , Have two product.
product 1 ) only binary with close license with price XXX
product 2 ) binary with source code, with license to use source code with price YYY
Q) can i change license of my code.
AS long as you are copyright holder of software packages, you are allow to changes license . If fact, you have 10 customer, then you can give your package A with 10 different license.
I am also having some confusion but above are correct upto to my knowledge , Do let me know if something is incorrect.