documentclass[12pt]{article}
usepackage{longtable}
begin{document}
begin{center}
begin{longtable}{|c|c|c|c|}
caption{A simple longtable example}\
hline
textbf{First entry} & textbf{Second entry} & textbf{Third entry} & textbf{Fourth    entry} \
hline
endfirsthead
multicolumn{4}{c}%
{tablename thetable -- textit{Continued from previous page}} \
hline
textbf{First entry} & textbf{Second entry} & textbf{Third entry} & textbf{Fourth entry} \
hline
endhead
hline multicolumn{4}{r}{textit{Continued on next page}} \
endfoot
hline
endlastfoot
1 & 2 & 3 & 4dddddddddddd asdfdasfasdf asödflkjasdf asdfasdfasdf \ 1 & 2 & 3 & 4 \ 1   & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \
1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \
1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \
1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \
1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \
1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \
1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \
1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \
1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \
1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \
1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \
1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \ 1 & 2 & 3 & 4 \
end{longtable}
end{center}
end{document}

begin{longtable}{|c|c|c|c|}

begin{longtable}{|c|c|c|p{6cm}|}