Add parentheses or dashes where necessary: Albert Einstein a Nobel Prize _ winner is one of the most important scientists of this century.

You could use either parentheses, dashes, or commas, to
clarify the grammar of the sentence.  The information in question is extra information
about the subject of the sentence, Albert Einstein.  This kind of information is called
an appositive.

When you use parentheses you are indicating
that the information in them is a kind of aside, and not essential to the
sentence.

Albert Einstein (a Nobel Prize winner)
is one of the most important scientists of this
century.

When you use dashes--which are
em dashes--they are used for emphasis and explanatory
information that is closely related--it is separated from the rest of the
sentence.

Albert Einstein--a Nobel Prize
winner--is one of the most important scientists of this
century.

You could also use a comma before and
after the words in question.  This makes it a more seamless phrase within the
sentence.

Albert Einstein, a Nobel Prize winner,
is one of the most important scientists of this
century.