Select any selection tool. Trace the fragments of complex shapes with smooth lines it is better to use the Lasso Tool (Lasso) and the Magnetic Lasso Tool ("Magnetic lasso"). For the selections, consisting of straight lines, is easier to use the Polygonal Lasso Tool ("Polygonal lasso").
Not to spoil the main image failed change, after selecting the snippet, you copy it to a new layer Ctrl+J. press and Hold Ctrl and click on the icon of this layer. Around the fragment will appear again in the selection.
On the toolbar, click any of groups L or M and right-click within the selection. In the drop-down menu, select the command Make Work Pass ("New working path"). In the new window set the value for Tolerance ("Tolerance") – the lower the value, the more accurate the contour will coincide with image boundaries.
Now you can adjust the working path. On the toolbar, choose the Direct Selection Tool ("Management allocation") and right click on the contour where you want to change its shape. Note the command Add Anchor Point ("Add anchor point"). Hook point with the left mouse button and drag it, changing the shape of the contour. Press Esc when the result suits you
Select the Brush tool (Brush) and in the properties pane, set the parameters – the color and width. Again select Add Anchor Point, call the context menu right click the mouse and select Stroke Pass ("Stroke path").
In a new window in the line Tool ("Tool") open the list and select Brush. The stroke is the same width and color, which you chose to brush. If you want the width of the stroke has changed, check the box Pressure ("Push"). Call the context menu right click the mouse and select the Delete command Pass ("Delete contour").