Use this application to describe your tree analysis from the top down rather than nested. It then generates the nested form which you can use in LingTree.
S => NP1 VP
NP1 => Lee
VP => V NP2
V => gets
NP2 => Det N
Det => the
N => idea
Nested: (S (NP (Lee ))(VP (V (gets ))(NP (Det (the ))(N (idea )))))
LingTree https://software.sil.org/lingtree/ - Use this software to generate the syntactic tree.
SynTree http://mshang.ca/syntree/ - Web-based app for creating trees (uses square brackets instead of parentheses).