How do I transfer learning in keras.net

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C#

like this in python:
from tensorflow.keras.optimizers import Adam

x = layers.Flatten()(pre_trained_model.output)

x = layers.Dense(1024, activation='relu')(x)
x = layers.Dropout(0.2)(x)

x = layers.Dense(1, activation='sigmoid')(x)

model = Model(pre_trained_model.input, x)

model.compile(optimizer = Adam(lr=0.001),
loss = 'binary_crossentropy',
metrics = ['acc'])

i want to do in keras.net.I don't know how to get the output and input layer of the model for example Resnet50

What I have tried:

like this in python:
from tensorflow.keras.optimizers import Adam

x = layers.Flatten()(pre_trained_model.output)

x = layers.Dense(1024, activation='relu')(x)
x = layers.Dropout(0.2)(x)                  

x = layers.Dense(1, activation='sigmoid')(x)           

model = Model(pre_trained_model.input, x) 

model.compile(optimizer = Adam(lr=0.001), 
              loss = 'binary_crossentropy', 
              metrics = ['acc'])

i want to do  in keras.net.I don't know how to get the output and input layer of the model for example Resnet50