Highlight cell range if 1 particular cell in range contains data

Select D3

Conditional Formatting
New Rule
Use a formula to determine...

=($D$3="x")

Format as required
Use Format painter (paintbrush icon) to copy to other cells

Okay then try the following steps:-
1. Select B3:H3. (This would be the range to which Conditional Formatting applies.)
2. Then Go to Home Tab >> Conditional Formatting >> New Rule >> Formula to determine which cell to format.
3. Type following formula there.
=$D3<>""
4. Select the appropriate highlighting style using Format. Click OK.
5. Now Put x in D3. B3:H3 should get highlighted.

okay then
1. Select columns B:H
2. Use Conditional Formatting formula
=$D1<>""
instead.

hmm..!
but "Applies to" Range should atleast be D2:D200.

Edit:- In my solution, I have used Dollar($) sign to apply formatting to all the columns in each row of 'Applies to' Range. $ sign has been put before Columns Alphabet (ie. D) which means excel will format all the Columns in each row. In simple words:-
$D1 means format all columns if criteria($D? <>"")mets .
D$1 means format all rows for first column in 'Applies to' Range.
$D$1 means format all rows and columns if criteria ($D$1<>"") mets.