Here are my links on conditional value lists. You probably only need to apply "option 1" of the first link.
There's a lot of overlap between the first two links so you can read one and skim the other. The demo file gives you several examples of different conditional value lists so you can examine them to see how they are set up. If you are using FileMaker 12, you can open this demo file from your File menu to get a converted copy of the demo file that you can examine in FileMaker 12.
The last link discusses how to set up a chain of conditional value lists where the value selected in each conditional value list controls the values listed in the next value list.
Forum Tutorial: Custom Value List?
Knowledgebase article: http://help.filemaker.com/app/answers/detail/a_id/5833/kw/conditional%20value%20list
Hierarchical Conditional Value lists: Conditional Value List Question
Feel free to post follow up questions here if those links aren't enough to get your value lists working correctly.
I have tried to look at the demo file and read those topics. I am also novice. But cannot find a solution to include at drop-down list only those elements with "yes" value, without placing additional field in layout. would be thankful for any simple explanation. Thanks.
Did you read option 1 in the tutorial link?
This adds a calculation field but it need not be placed on any layout.
Yes the option 1 seems to work in this case, thanks.
I don't know how to apply option 2 from the same tutorial, though. And because it is more 'flexible' I would like to know how to create this relation that is limiting records.
Option 2 requires setting up a relationship. This, in turn, requires adding a match field to your original table in order to match to just records of that category. In your case, that requires either a text field or a calculation returning text with the text "yes" in that field.
MainTable::constYes = ValuesTable::Current User
What makes it more flexible, is that if you use a text field in place of constYes, You can put "no" in the field and then your value list changes to a list of all records that are NOT current users. Since you may already have a different relationship in place between the same two tables, you may have to add a new Tutorial: What are Table Occurrences? of the values table to keep your current relationship unmodified and set the value list to list values from this new table occurrence.
You'll have to judge whether or not that is a useful gain in flexibility or not.