What have you tried? Did you check Documentation?
Distribution parameters estimation:
Estimate the distribution parameters from sample data:
edist = EstimatedDistribution[sample, HalfNormalDistribution[\[Theta]]]
Out[] = HalfNormalDistribution[4.0821]
Compare the density histogram of the sample with the PDF of the estimated distribution:
Show[Histogram[sample, Automatic, "PDF"], Plot[PDF[edist, x], {x, 0, 1}, PlotStyle -> Thick]]
